This was happening with a cheap PS/2 mouse which came with the (also cheap) keyboard as a combo. On the DE2-70, as I did not have a chance yet to prepare an adapter for PS/2 mouse on the DE2.
Luckily I had one of those green adapters which converts from USB to PS/2 mouses, so I tried an USB mouse with that and it worked fine. Go figure.
Excellent - glad to hear it's working
The video quality of the DE2-70 is a bit worse than the DE2. Like if there's some little color "leaking" or "smeared" from the white, which makes the image appear a bit blurred. Just a little bit, not more than a real Amiga would show on a CRT monitor, but enough to bother me, lol.
Hmmm - are there maybe some EMI suppression capacitors on the video out that are either not present or smaller on the older DE2?
I want to test now the hard disk emulation and sound. Let's see.